Unloader governor device



Dec. 22, 1936. p, X- 2,065,199

UNLOADER GOVERNOR DEVICE Filed March 25, 1935 I.\'I 'ENTOR. EVERETT P.SEXTON .4 TTORNEY.

Patented Dec. 22, 1936 UNITED STATES PATENT OFFICE UNLOADER GOVERNORDEVICE Application March 25, 1933, Serial No. 862,713

This invention relates to fluid compressors, and more particularly tomeans for controlling the loading and unloading of the compressor.

With a continuously operating compressor, there is a tendency for thestorage reservoir to become overcharged unless means are provided forunloading the compressor when the pressure of the fluid in the reservoirattains the predetermined amount.

It has heretofore been proposed to provide a fluid pressure actuatedunloading device for compressors in which is incorporated a flexiblediaphragm for operating a lever which, in turn, acts on the unloadingvalve of the compressor to unseat the same, thereby permitting thecompressed fluid to pass to the atmosphere instead of to the reservoir.

It has also heretofore been proposed to provide a governor device whichis adapted to be connected to the unloading mechanism of a compressorand also to the reservoir which is supplied with fluid under pressure bythe compressor, so as to automatically effect the operation of thecompressor unloading mechanism when the pressure of the fluid in thereservoir exceeds a predetermined amount.

The principal object of my invention is to provide an improved governordevice of the above character which is simple in construction and Ipositive in action, which has few operating parts and which isadjustable, so as to be operated by various pressures.

In the accompanying drawing, the single flgure is a sectionaldiagrammatic view of a portion of a fluid compressor having associatedtherewith an unloading means and a compressor unloader governorconstructed in accordance with the invention.

Referring to the drawing, the governor device may be used in connectionwith a compressor comprising a cylinder l, shown in part, and having acylinder head 2 provided with a valve chamber 3, containing the usualdischarge valve 4, for controlling communication from the fluidcompressor to the usual storage reservoir 5, which is connected to thevalve chamber 3 by a pipe 6.

An unloading valve 1' controls communication from the compressorcylinder i to the atmosphere, said valve having an operating stem 8which extends through a bore in the cylinder head 2 and which carries atits outer end a spring follower 9 which is subject to the pressure of acoil spring Ill acting through said stem to urge the valve 1 to itsseat.

Pivotally mounted on a pin ll carried by the head 2 is a lever l2 havinga long arm l3 which is adapted to engage the end of the valve stem 8.

The short arm ll of the lever I2 is adapted to engage the end of a stemamociated with a diaphragm follower plate l6, which is actuated 5 by adiaphragm I I. The chamber l8 in the cylinder head 2, at one sideiof thediaphragm I1, is connected to a pipe l9, which leads to the improvedgovernor device, for a purpose to be fullydescribed hereinafter.

The governor device may comprise a casing having a valve chamber 2|containing a slide valve 22, which chamber is continuously connected tothe pipe 6 through a pipe 23. Said slide valve is provided with a cavity24 and is adapted 15 to cooperate with a valve seat 25 provided withports, as will be hereinafter described. The slide valve 22 isoperatively connected to a stem 50, said slide valve and stem beingadapted to be operated through the medium of spaced flexible 20diaphragms 26, 21 and 28 which are secured in the casing, the area ofthe diaphragm 26 being greater than that of the diaphragm 21, which inturn, has a greater area than that of the diaphragm 23. 5

The flexible diaphragm 26 separates the slide valve chamber 2| from achamber 29 which is constantly connected to the atmosphere through a Ipassage 30, said diaphragm being clamped between a flange 3|, providedat one end of the 30 stem 50, and a follower plate 32, through themedium of a headed screw-33 which has screwthreaded engagement with thestem 50, there being a member 34 clamped to the follower by means ofsaid screw. 35

Contained in the chamber 29 and interposed between and engaging themember 34 and an adjusting nut 35 having screw-threaded engagement'withthe casing, is a coil spring 36. The adjusting nut 35 may be locked inposition by 40 means of a locking member 31 which has screwthreadedengagement with said nut and is adapted to abut the casing 23.

One side of the diaphragm 21 engages a flange 38 provided at the otherend of the stem 50. Spaced from the diaphragm 21 by means of a followerplate 48 is a diaphragm 28, and engaging the outer face of the diaphragm28 is a follower plate 39. Extending through said follower plates andthrough said diaphragms and having screw- 60 threaded connection withthe stem 50, is a headed screw 40 by means of which said diaphragms aresecured together and to the stem 50.

Intermediate the diaphragms 21 and 28 is a chamber II which iscontinuously connected by a passage 42 to a passage 43 which connectswith glee pipe I! and also leads to the slide valve seat The diaphragm28 separates the chamber 4| from a chamber 44 which is continuouslyconnected to the atmosphere through a passage 45.

In operation, assuming that the nut 36 has been adjusted for thepressure at which it is desired to unload the compressor and that thepressure of the fluid in the slide valve chamber 2| and in the connectedreservoir 5 is below this pressure, the spring 36 will act to maintainthe diaphragms 26, 21 and 28 and the slide valve 22 in the positionshown in the drawing, in which the diaphragm follower plate 3| engagesthe stop shoulders 46 provided in the casing 26 and in which the passage43 is connected through the cavity 24 in the slide valve 22 to anatmospheric passage 41. Since the chamber 4| is connected by the passage42 to the passage 43 and since the chamber l8 in the unloading device isalso connected to the passage 43 by the pipe l3, said chambers areconnected to the atmosphere in the position of the slide valve 22 shownin the drawing.

The chamber l8 being connected to the atmosphere, the diaphragm I1 willnot cause the lever l2 to exert any appreciable pressure on the stem 6of the unloading valve, with the result that the spring III will holdsaid valve seated.

When the pressure of the fluid supplied by the compressor to thereservoir 5 and to the connected slide valve chamber 2| has increased toa point when the pressure exerted by the fluid in said chamber on theright hand face of the diaphragm 26 exceeds the pressure of the spring36 plus the pressure exerted by the fluid in the chamber 2| on the lefthand face of the diaphragm 21, the diaphragms 26, 21 and 23 and handface of the diaphragm 21 approaches equalization with the pressure ofthe fluid in chamber 2| acting on the opposite face of said diaphragm,the pressure of the fluid in chamber 2| acting on the right hand face ofthe diaphragm 26 will'become increasingly effective, with the resultthat the diaphragms 26, 21 and 28, with the stem 50 and the slide valve22, will be moved positively to the full cut-out position, in which thefollower plate 38 engages a shoulder 43 provided in the casing 20 and inwhich the passage 43 is fully open to the slide valve chamber 2|.

It will be noted that the pressure of the fluid in chamber 4| also actson the diaphragm 28. but since said diaphragm has a smaller area thanthat of the diaphragm 21, there will be an unbalanced pressure of fluidin chamber 4|, due to the differential area of the diaphragm 21, whichacts on the diaphragm 21 to urge same toward the left.

With the passage 43 opened to the valve chamber 2|, fluid under pressureis supplied from the reservoir 5 to the diaphragm chamber I8 throughpipe 6, pipe 23, chamber 2|, passage 43, and pipe so that the lever I2is actuated to cause the stem 3 to move downwardly and thereby unseatthe valve 1. The compressing cylinder I being then opened to theatmosphere, the compressor operates without compressing fluid into thereservoir 6.

When the fluid pressure in the reservoir 6 and in the connected chamber2| has fallen to a point where the pressure of the spring 36 acting onthe left hand face of the diaphragm 26 exceeds the pressure of fluidacting in chamber 2| on the differential area of diaphragm 26 and inchamber 4| on the differential area of diaphragm 21, the diaphragms 26,21 and 26, with the stem 66 and the slide valve 22, will begin to movein a direction toward the right hand. As this movement progresses, theslide valve will cut oil. communication from the chamber 2| to thechamber 4| by way of passages 43 and 42, and the cavity 24 in said slidevalve will connect passage 43 to the atmospheric passage 41. With thisconnection established, the chamber 4| will be vented to the atmospherethrough the passages 42 and 43, cav-' ity 24, and the passage 41. Theventing of fluid under pressure from chamber 4| reduces the differentialfluid pressure acting in chamber 4| on diaphragm 21, so that the partswill move positively to their right hand, or cut-in position, in

which the diaphragm follower 3| engages the shoulder 46 and the passage43 is fully open to the passage 41, as shown in the drawing. It will benoted that with the chamber 4| vented, the diaphragm 28 becomesineffective, since the chamber 44 is also vented.

I With the slide valve 22 in the cut-in position, wherein the passage 43is connected to the atmosphere, as above described, fluid is vented fromthe diaphragm chamber l8 through the pipe l9, passage 43, cavity 24 inthe slide valve and the atmospheric passage 41. With the pressure thusrelieved from the arm H of the lever i2, the spring III will act toshift the valve 1 upwardly to its seat. The compressor then operates tocompress fluid into the reservoir 5.

It will be understood that the cutting-out pressure ofthe governordevice is determined by the pressure exerted by the spring 36, combinedwith the relation existing between the areas of the diaphragms 26 and21, and, that the cutting-in pressure is determined by the pressureexerted by said spring, combined with the relation existing between theareas of the diaphragms 26 and 28. To adjust the spring 36, the member31 is unscrewed from the nut 35, which is then turned as required toestablish the desired cutting-in pressure or the desired cutting-outpressure.

It will be apparent from the foregoing that I have provided an unloadergovernor device which is simple in construction and positive in action.

While one illustrative embodiment of the invention has been described indetail, it is not my intention to limit its'scope to that embodiment orotherwise than by the terms of the appended claims.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. A device for controlling the operation of a fluid compressorunloader, comprising a plurality of interconnected movable abutments,tensioned biasing means for urging said abutments in one direction, saidabutments being differentially subjected to the pressure of fluidcompressed by the compressor and thereby urged in the oppositedirectlon, valve means operably responsive to the movement of saidabutments occasioned by variations in the fluid pressure for controllingthe operation of the unloader, and means for varying the tension of saidbiasing means to vary the force applied by said biasing means to saidabutments.

2. A device for controllingthe operation of a fluid compressor unloader,comprising a plurality of interconnected movable abutments, springbiasing means for urging said abutments in one direction, stop meansadapted to be engaged by one of said abutments for limiting the movementof said abutments in said one direction, said abutments being subjectedto the pressure of fluid compressed by the compressor and thereby urgedin the opposite direction, stop means adapted to be engaged by anotherof said abutments for limiting the movement of said abutments in saidopposite direction, and valve means operated by movement of saidabutments occas oned by variations in the fluid pressure forestablishing a communication through which fluid under pressure isvented from the unloader when said abutments are moved to their limit inthe said one direction and for establishing a communication throughwhich fluid under pressure is supplied to the unloader when saidabutments are moved to their limit in the said opposite direction,whereby to control operation of the unloader.

3. A device for controlling the operation of a fluid compressorunloader, comprising a pair of connected movable abutments of differentareas and having a chamber therebetween, biasing means constantly urgingthe abutments in one direction. said abutments being constantly urged inthe opposite direction in opposition to said biasing means by thedifferential force of fluid acting on said abutments within saidchamber,

and valve means operated to diflerent positions by said abutments uponvariations in the pressure in said chamber, said valve means beingeffective in one position thereof to establish a communication throughwhich fluid under pressure is vented to atmosphere from the compressorunloader and effective in a diiferent position to establish acommunication through which fluid under pressure is supplied to theunloader. whereby to control loading and unloading of the compressor.

4. A device for controlling the operation of a fluid compressorunloader, comprising a pair of connected movable abutments of differentareas and having a chamber therebetween, biasing means constantly urgingthe abutments in one direction, said abutments being constantly urged inthe opposite direction in opposition to said biasing means by thedifferential force of fluid under pressure compressed by the compressorand acting on said abutments within said chamber, and valve meansoperated to different positions by said abutments upon variations in thepressure in said chamber, said valve means being effective in oneposition thereof to establish a communication through which fluid underpressure is vented to atmosphere from the compressor unloader to causeloading of the compressor and effective in a different position toestablish a communication through which fluid under pressure is suppliedto the unloader to cause unloading of the compressor. 1

5. A device for controlling the operation of a fluid compressorunloader, comprising a pair of connected movable abutments of difierentareas and having a chamber therebetween, biasing means constantly urgingthe abutments in one direction, said abutments being constantly urged inthe opposite direction in opposition to said biasing means by thedifierential force of fluid under pressure compressed by the compressorand acting on said abutments within said cham-' ber, and valve meansoperated to diilerent positions by said abutments upon variations in thepressure in said chamber, said valve means being efiective in oneposition thereof to establish a communication through which fluid underpressure is vented to atmosphere from the compressor unloader to causeloading of the compressor and effective in a diiferent position toestablish a communication through which fluid under pressure is suppliedfrom said chamber to the unloader to cause unloading of the compressor.

6. A device for controlling the operation of a fluid compressorunloader, comprising a pair of connected movable abutments of differentareas and having a chamber therebetween, biasing means constantly urgingthe abutments in one direction, said abutments being constantly urged inthe opposite direction in opposition to said biasing means by thediiiferential force of fluid under pressure compressed by the compressorand acting on said abutments within said chamber, valve means having oneposition in which it establishes a communication through which fluidunder pressure is vented from the unloader to cause loading of thecompressor and having a difierent position in which it establishes acommunication through which fluid under pressure is supplied to theunloader to cause unloading of the compressor, said valve means beingmoved from said one position toward said different position uponmovement of the abutments in said opposite direction occasioned by anincrease in the pressure in said chamber to a certain uniform pressure,and means efi'ective upon movement of said valve means from said oneposition toward said different position to cause an additional force tobe imposed on the abutments urging them in said opposite direction sothat said valve means is moved positively to said different position andso that movement of the abutments in said one direction to return thevalve means toward the said one position is prevented until the pressureof the fluid in said chamber has reduced to a second certain uniformpressure which is less than the flrst said certain uniform pressure.

7. A device for controlling the operation of a fluid compressorunloader, comprising a pair of connected movable abutments of diiferentareas and having a chamber therebetween, biasing means constantly urgingthe abutments in one direction, said'abutments being constantly urged inthe opposite direction in opposition to said biasing means by thedifferential force of fluid under pressure compressed by the compressorand acting on said abutments within said chamber, valve means having oneposition in which it establishes a communication through which fluidunder pressure is vented from the unloader to cause loading of thecompressor and having a said difierent position to cause anadditionalforce to be imposed on the abutments urging them in saidopposite direction so that said valve means is moved positively to saiddifferent position and so that movement of the abutments in said onedirection to return the valve means toward the said one position isprevented until the pressure of the fluid in said chamber has reduced toa second certain uniform pressure which is less than the first saidcertain uniform pressure, said last means being effective upon return ofsaid valve means toward said one position to cause removal of theadditional force so that said valve means is returned positively to saidone position and so that the valve means will not, be moved toward thesaid different position thereof until the pressure in said chamber hasagain increased to the first said certain uniform pressure.

' 8. A device for controlling the operation of a fluid compressorunloader, comprising a pair of connected movable abutments of differentareas and having a chamber therebetween, biasing means constantly urgingthe abutments in one direction, said abutments being constantly urged inthe opposite direction in opposition to said biasing means by thedifferential force of fluid under pressure compressed by the compressorand acting on said abutments within said chamber, and valve means havingone position in which it establishes a communication through which fluidunder pressure is vented from the unloader to cause loading of thecompressor and having a different position in which it establishes acommunication through which fluid under pressure is supplied to theunloader to cause unloading of the compressor, said valve means beingmoved from said one position toward said difierent position uponmovement of the abutments in said opposite direction occasioned by anincrease in the pressure in said chamber to a certain uniform pressure,said valve means being effective upon movement toward said differentposition thereof to establish a communication through which fluid underpressure is supplied to act on .the outer face of the smaller of saidabutments to increase the force opposing said biasing means so that saidvalve means is moved positively to said different position and so thatmovement'of said abutments in the said one direction to return the valvemeans to said one position is prevented until the pressure in saidchamber is reduced to a second certain uniform pressure which is lessthan the first said certain uniform pressure;

9. A device for controlling the operation of a fluid compressorunloader, comprising a pair of connected movable abutments of differentareas and having a chamber therebetween, biasing means constantly urgingthe abutments in one direction, said abutments being constantly urged inthe opposite direction in opposition to said biasing means by thedifferential force of fluid under pressure compressed by the compressorand acting on said abutments within said chamber, and valve means havingone position in which it establishes a communication through which fluidunder pressure is vented from the unloader to cause loading of thecompressor and having a different position in which it establishes acommunication through which fluid under pressure is supplied to theunloader to cause unloading of the compressor, said valve means beingmoved from said one position toward said different position uponmovement of the abutments in said opposite: direction occasioned by anincrease in the pressure in said chamber to a certain uniform pressure,said valve means being effective upon movement toward said differentposition thereof to establish acommunication through which fluid underpressure is supplied to act on the outer face of the smaller of saidabutments to increase the force opposing said biasing means so that saidvalve means is moved positively to said diiferent position and so thatmovement of said abutments in the said one direction-to return the valvemeans to said one position is prevented until the pressure in saidchamber-is reduced to a second certain uniform pressure which is lessthan the first said certain uniform pressure and effective uponmovementtoward the said one position thereof to establish acommunication through which fluid under pressure is vented from theouter face of the smaller abutment so that said valve means is movedpositively to said one position and so that said abutments will not bemoved in the said opposite direction to move the said valve means fromsaid one position toward said different position until the pressure insaid chamber again increases to said certain uniform pressure.

10. A device for controlling the operation of a fluid compressorunloader, comprising a pair of connected movable abutments of differentareas and having a chamber therebetween, biasing means constantlyurgirfg the said abutments in one direction, said abutments being urgedin the opposite direction in opposition to said biasing means by thedifferential force of the fluid pressure acting in said chamber on saidabutments, valve means operated to different positions by said abutmentsupon variations in the pressure of fluid in the said chamber, said valvemeans being effective in one position thereof to establish acommunication through which fluid under pressure is released from theunloader to effect loading of the compressor and a communication throughwhich the outer face of the smaller of the abutments is opened toatmosphere, said abutments being ,moved in said opposite direction uponan increase in the pressure in said chamber to a certain uniformpressure to move said valve means to a second position wherein itestablishes a communication through which fluid under pressure issupplied to the unloader to cause it to unload the compressor and acommunication through which fluid under pressure is supplied to act onthe outer face of the smaller of said abutments and increase the forceurging said abutments in said opposite direction.

11. A device for controlling the operation of a fluid compressorunloader, comprising three axially disposed connected movable abutmentsof different areas respectively, a first chamber between one endabutment and the intermediate abutment, a second chamber between saidintermediate abutment and the other end abutment, biasing meansconstantly urging said abutments in one direction, said abutments beingconstant ly urged in the opposite direction in opposition to saidbiasing means by the differential force of fluid under pressurecompressed by the compressor and acting in said first chamber on saidone end abutment and said intermediate abutment, and valve meansoperated by the abutments upon an increase in the pressure of the fluidin said first chamber to a certain uniform pressure from one position,in which it establishes a communication through which fluid underpressure is vented from the unloader to cause loading of the compressor,to a second position, in which it establishes a communication throughwhich fluid under pressure is supplied to the unloader to causeunloading of the compressor, said valve means being efiective in saidone position to establish a communication through which said secondchamber is vented to the atmosphere and eifective in said secondposition to establish a communication through which fluid under pressureis supplied to said second chamber, the differential force of the fluidunder pressure acting in said second chamber on the said intermediateabutment and the said other end abutment being efiective to urge theabutments in the said opposite direction in opposition to said biasingmeans whereby the said biasing means is ineffective to return saidabutments in said one direction to move the valve means from the secondposition thereof to the said one position thereof until the pressure ofthe fluid in the said first chamber reduces to a second certain uniformpressure which is less than the first said certain uniform pressure.

12. A device for controlling the operation of a fluid compressorunloader, comprising three coaxially disposed connected movableabutments of different areas respectively, a first chamber between oneend abutment and the intermediate abutment, a second chamber betweensaid intermediate abutment and the other end abutment, biasing meansconstantly urging said abutments in one direction, said abutments beingconstantly urged in the opposite direction in opposition to said biasingmeans by the difierential force of fluid under pressure compressed bythe compressor and acting in said first chamber on said one end abutmentand said intermediate abutment, and valve means operated by theabutments upon an increase in the pressure of the fluid in said firstchamber to a certain uniform pressure from one position, in which itestablishes a communication through which fiuid under pressure is ventedfrom the unloader to cause loading of the compressor, to a secondposition, in which it establishes a communication through which fiuidunder pressure is supplied to the unloader to cause unloading of thecompressor, said valve means being efiective in said one position toestablish a communication through which said second chamber is vented tothe atmosphere and effective in said second position to establish acommunication through which fluid under pressure is supplied from saidfirst chamber to said second chamber, the difierential force of thefluid under pressure acting in said second chamber on the saidintermediate abutment and the said other end abutment being efiective tourge the abutments in the said opposite direction in opposition to saidbiasing means whereby the said biasing means is ineifective to returnsaid abutments in said one direction to move the valve means from thesecond position thereof to the said one position thereof until thepressure of the fluid in the said first chamber reduces to a secondcertain uniform pressure which is less than the first said certainuniform pressure.

EVERETT P. SEXTON.

